#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<long long,long long>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	long long ans = 0;
	vector<P>a(n);
	rep(i, n) {
		cin >> a[i].second >> a[i].first;
	}
	sort(allR(a));
	vector<vector<long long>>dp(n + 1, vector<long long>(n + 1, LINF));
	dp[0][0] = 0;
	rep(i, n)rep(j, n) {
		if (LINF == dp[i][j])continue;
		chmin(dp[i + 1][j + 0] , dp[i][j] + a[i].second + a[i].first * (i - j));
		chmin(dp[i + 1][j + 1] , dp[i][j]);
	}
	ans += dp[n][n / 3];
	cout << ans << endl;
	return 0;
}